Project Summary/Abstract People with Treatment Resistant Late-Life Depression (TRLLD) are at very high risk for suicide (including suicidal ideation and/or behavior) as well as neurocognitive impairment and decline to dementia. This proposed Administrative Supplement leverages our funded R01 ?Neurocognitive and Neuroimaging Biomarkers: Predicting Progression Towards Dementia in Patients with Treatment Resistant Late-Life Depression? (OPTIMUM-Neuro) to examine the relationship between suicide risk and brain health in a large group of patients with TRLLD. Additional measures of suicide risk (lifetime history of and current suicidal ideation and behavior) will be obtained and neurocognitive diagnosis will be adjudicated using expert consensus conferences for the 300 participants already recruited in OPTIMUM-Neuro as of May 2019 and an additional 150 recruited over the supplement's one-year time frame. The data will be used to examine both history of suicidal ideation and behavior (collected through this supplement) and trajectories of suicidal ideation and behavior over one year (collected through this supplement during the OPTIMUM-Neuro follow-up time period). The aims of the proposed research will examine in people with TRLLD (1) whether assessing and including information about neurocognitive functioning improves our prediction of suicide risk and whether a novel measure of real-life decision-making (through the Research Domain Criteria (RDoC) framework) adds to our ability to predict one's suicide risk; (2) whether early-onset and late-onset suicidal ideation and/or risk are associated with specific and different neurocognitive impairments; and (3) whether risk of suicide is higher in people with TRLLD and a diagnosis of Mild Cognitive Impairment than in those with no cognitive diagnosis, and whether it is especially high in those whose impairment is caused by cerebrovascular disease, as compared with Alzheimer's disease. In sum, OPTIMUM-Neuro provides a unique opportunity to examine the relationship between suicide risk and cognitive impairment and decline in a large and well-characterized longitudinal study of community-dwelling older individuals particularly vulnerable to both suicidal behavior and dementia due to TRLLD.